[SCSI] Disable WRITE SAME for RAID and virtual host adapter drivers

Some host adapters do not pass commands through to the target disk
directly. Instead they provide an emulated target which may or may not
accurately report its capabilities. In some cases the physical device
characteristics are reported even when the host adapter is processing
commands on the device's behalf. This can lead to adapter firmware hangs
or excessive I/O errors.

This patch disables WRITE SAME for devices connected to host adapters
that provide an emulated target. Driver writers can disable WRITE SAME
by setting the no_write_same flag in the host adapter template.

[jejb: fix up rejections due to eh_deadline patch]
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Cc: stable@kernel.org
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/scsi/3w-sas.c b/drivers/scsi/3w-sas.c
index c845bdbeb6c0..4de346017e9f 100644
--- a/drivers/scsi/3w-sas.c
+++ b/drivers/scsi/3w-sas.c
@@ -1600,7 +1600,8 @@ static struct scsi_host_template driver_template = {
         .cmd_per_lun            = TW_MAX_CMDS_PER_LUN,
         .use_clustering         = ENABLE_CLUSTERING,
         .shost_attrs            = twl_host_attrs,
-        .emulated               = 1
+        .emulated               = 1,
+        .no_write_same          = 1,
 };
 
 /* This function will probe and initialize a card */